, for example, the planet coming around the sun like this, when it goes by jupiter, it sort of wobbles a little bit and that was to be expected because there's an interaction between the planet and jupiter too like the planet, uranus, okay? but when uranus is way out here and jupiter is over here, they found out that uranus was acting a little differently out there too. they call that a perturbation and they found out that the planet uranus was undergoing a perturbation where no other planet was and the popular idea at the time was, well, way out there the law of gravity, newton's majestic law of gravity is obviously breaking down, but not everyone believed that. a couple of mathematician types made some calculations as to where another planet would have to be to cause those perturbations and they made about the same time in history. one was an englishman, the other one was a frenchman and the englishman reported his hypothesis and sent it to the observatory in greenwich, england. when the observatory type got his letter, opened it up and says, what's this? some mathematician is tellin